In the electronics industry, manufacturers of semiconductor devices such as integrated circuits (IC) produce devices in a form of packages or IC chips that contain semiconductor circuitry capable of numerous electronic processing and computation tasks. During manufacturing and testing of such IC chips, the chips are subject a variety of tests such as burn-in tests and electrical property tests to ensure the chips operate properly from a quality and performance perspective prior to shipping to customers. While undergoing such tests, the IC chips are typically not permanently soldered to IC chip testing equipment. Rather, such chips are placed into a test socket apparatus which can temporarily yet firmly hold the chips as the tests are performed. The sockets also allow a chip mounted in a socket to be transferred from one test station to another without requiring the chip itself to be inserted and removed from the socket, thus resulting in less wear and tear on the physical IC chip.
A typical IC chip has a large number of electrical leads that extend from one or more surfaces of the chip. Depending upon the specific chip or package configuration, the electrical leads of an IC chip may be pins, leads, terminals or balls or another type of connector that are often arranged in a matrix, array or other uniform layout. Conventional test sockets typically grasp the electrical leads, pins, balls or connectors of a chip undergoing testing using respective contacts for each lead. As an example, a Ball Grid Array (BGA) package is a type of physical IC chip configuration that includes small solder balls that extend downwards from a lower surface of the chip. Each ball serves as an electrical input/output path to circuitry contained within the IC chip.
Issued U.S. Pat. Nos. 6,027,355 and 6,287,127, owned by assignee of this instant application, describe a socket apparatus designed to hold a BGA package during testing. The entire teachings and contents of these referenced issued patents are hereby incorporated by reference in their entirety. The socket apparatus described in the aforementioned patents provide a main socket body for removably loading an electric part such as an IC chip that has an arrangement or array of lead terminals in a prescribed pattern that get inserted into the socket. The socket includes an array of contact makers, arms or fingers arranged on the main socket body in conformity with the pattern of terminal leads of the chip. Each contact maker or contact has a pair of openable and closeable arm-shaped contacts or fingers capable of flexibly opening and closing in compressive engagement holding each respective terminal lead of the electric part. The socket provides a sliding mechanism that uniformly causes the arms of each contact top to open in unison as the IC chip is lowered into the socket, thus providing a zero insertion force (ZIF) socket that does not strain the contacts of the chip during insertion (and during removal) of the chip into and out of the socket.
When the chip is in place, the arms are released and each set of arms provides compressive force on a respective contact (e.g. ball or lead from the chip) to make a proper electrical connection. At this time, the terminal leads of the electrical part are firmly sandwiched by the respective arm-shaped contacts as a result of the face to face relation of the pressure contacts of the arm-shaped contact thereby obtaining a state of satisfactory electrical connection. After testing is complete, just prior to chip removal from the socket, the sliding mechanism is engaged to again uniformly open the arms of each contact to provide for no force exerted on the leads of the chip as it is removed from the socket. In this manner, the socket apparatus can be used to receive a chip, perform testing, and allow for removal of the chip over and over for numerous chips.